A practical guide for commercial energy buyers navigating the NEM and WEM
The National Electricity Market (NEM) is a wholesale spot market that covers five states on Australia's east coast: New South Wales, Victoria, South Australia, Queensland, and Tasmania. Operated by AEMO, it is one of the longest interconnected power systems in the world, stretching over 5,000 kilometres.
Every five minutes, AEMO's dispatch engine (NEMDE) determines which generators run and at what price. Generators submit bids specifying how much capacity they will offer at up to 10 price bands, ranging from the market floor of −$1,000/MWh to the market price cap of $17,500/MWh. The dispatch engine stacks bids from cheapest to most expensive until demand is met. The price of the last megawatt dispatched sets the spot price for that interval.
This produces 288 spot prices per day in each of the five NEM regions. Since five-minute settlement was introduced in October 2021, generators and loads are settled financially at these 5-minute intervals rather than the previous 30-minute averages.
Wholesale electricity prices reflect the real-time balance of supply and demand. The key drivers are:
Western Australia's Wholesale Electricity Market (WEM) is structurally different from the NEM. It operates on 30-minute trading intervals (48 per day), covers only the South West Interconnected System around Perth, and includes a capacity market that pays generators for availability regardless of dispatch.
The WEM is not interconnected with the NEM — there is no transmission link between Western Australia and the eastern states. This means WA1 prices are driven entirely by local conditions. The WEM tends to have lower average prices but less volatility than the NEM, partly due to its capacity market providing a revenue floor for generators.
Most large commercial and industrial electricity consumers do not purchase directly at the spot price. Instead, they use contracts to hedge their exposure:
Regardless of contract structure, understanding wholesale price dynamics helps buyers negotiate better rates, time contract renewals, and evaluate whether increasing spot exposure could reduce costs.
gridIQ categorises dispatch prices into colour-coded tiers to help users quickly assess market conditions. NEM and WEM use different thresholds:
Commercial energy buyers can translate wholesale market intelligence into concrete cost savings and risk management:
gridIQ provides live wholesale price data across all six Australian regions, with pre-dispatch forecasts, price alerts, and AI-powered analysis via Watt AI. View current prices on our live electricity prices page, explore historical trends in price history, or start your 14-day Professional trial for full access to forecasts, alerts, and API.